Can be done with a user defined function.

Function SortWithinCell(CelltoSort As Range, DelimitingCharacter As String, IncludeSpaces As Boolean) As String
CelltoSortString = WorksheetFunction.Substitute(CelltoSort.Value, " ", "")
MyArray = Split(CelltoSortString, DelimitingCharacter)
    For N = 0 To UBound(MyArray)
        For M = 1 To UBound(MyArray)
            
                If MyArray(M) < MyArray(M - 1) Then
                    TempValue = MyArray(M)
                    MyArray(M) = MyArray(M - 1)
                    MyArray(M - 1) = TempValue
                End If

        Next M
    Next N
For N = 0 To UBound(MyArray)
    SortWithinCell = SortWithinCell & MyArray(N) & DelimitingCharacter
Next N
SortWithinCell = Left(SortWithinCell, Len(SortWithinCell) - 1)
If IncludeSpaces = True Then SortWithinCell = WorksheetFunction.Substitute(SortWithinCell, ",", ", ")
End Function

Alt F11 to open the VBA editor. Insert - module. Paste in the above. Alt F11 back to worksheet,

In B1 enter

=SortWithinCell(A1,",",TRUE)

assuming starting string is in A1